1. Field of the Invention
The invention relates to a method for producing thin carbon products of controlled porosity useful, for example, as backing material for the catalyst layers of fuel cell electrodes, and for porous flow-through electrodes or impervious flow-by electrodes, such as those used in zinc-halogen batteries. Other electrochemically oriented applications also exist. The term "carbon" as used herein includes the graphite form of carbon.
2. Description of the Prior Art
It is known to use thin carbon structures as electrode substrates in electrochemical devices such as fuel cells and certain types of batteries. For example, U.S. Pat. No. 4,064,207 to DeCrescente et al. relates to a process for producing thin porous carbon sheets suitable for fuel cell electrode support plates wherein carbonizable filaments are chopped into short lengths, felted, sprayed with a resin binder, cured, and then carbonized. The disadvantages of this process include high raw material and processing costs, poor control of resin binder consistency compared to other carbonaceous materials, and relatively poor electrical conductivity and chemical stability of the finished product. Resins such as those employed in the reference have a relatively poor useful shelf life, especially at elevated temperatures, and viscosity changes with time during use. They also have poor graphitizability.